1 /* 2 * Copyright (c) 2010 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Alex Hornung <ahornung (at) gmail.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/vnode.h> 39 #include <sys/lock.h> 40 #include <sys/disk.h> 41 #include <sys/mount.h> 42 #include <sys/namecache.h> 43 #include <sys/nlookup.h> 44 #include <sys/proc.h> 45 #include <sys/devfs.h> 46 47 struct mount *synth_mp; 48 struct vnode *synth_vp; 49 static int synth_inited = 0; 50 static int synth_synced = 0; 51 52 struct vnode * 53 getsynthvnode(const char *devname) 54 { 55 struct vnode *vp; 56 struct nchandle nch; 57 struct nlookupdata nd; 58 struct ucred *cred = proc0.p_ucred; 59 int error; 60 61 KKASSERT(synth_inited != 0); 62 KKASSERT(synth_mp != NULL); 63 KKASSERT(synth_mp->mnt_ncmountpt.mount != NULL); 64 65 /* Sync devfs/disks twice to make sure all devices are around */ 66 if (synth_synced < 2) { 67 sync_devs(); 68 ++synth_synced; 69 } 70 71 error = nlookup_init_root(&nd, devname, UIO_SYSSPACE, NLC_FOLLOW, 72 cred, &synth_mp->mnt_ncmountpt, 73 &synth_mp->mnt_ncmountpt); 74 75 if (error) { 76 panic("synth: nlookup_init_root failed with %d", error); 77 /* NOTREACHED */ 78 } 79 80 error = nlookup(&nd); 81 if (error == 0) { 82 if (nd.nl_nch.ncp->nc_vp == NULL) { 83 kprintf("synth: nc_vp == NULL\n"); 84 return (NULL); 85 } 86 nch = nd.nl_nch; 87 cache_zero(&nd.nl_nch); 88 } 89 90 nlookup_done(&nd); 91 if (error) { 92 if (error != ENOENT) { /* Don't bother warning about ENOENT */ 93 kprintf("synth: nlookup of %s failed with %d\n", 94 devname, error); 95 } 96 return (NULL); 97 } 98 99 vp = nch.ncp->nc_vp; 100 /* A VX locked & refd vnode must be returned. */ 101 error = vget(vp, LK_EXCLUSIVE); 102 cache_unlock(&nch); 103 104 if (error) { 105 kprintf("synth: could not vget vnode\n"); 106 return (NULL); 107 } 108 109 return (vp); 110 } 111 112 static void 113 synthinit(void *arg __unused) 114 { 115 int error; 116 117 if ((error = vfs_rootmountalloc("devfs", "dummy", &synth_mp))) { 118 panic("synth: vfs_rootmountalloc failed with %d", error); 119 /* NOTREACHED */ 120 } 121 if ((error = VFS_MOUNT(synth_mp, NULL, NULL, proc0.p_ucred))) { 122 panic("synth: vfs_mount failed with %d", error); 123 /* NOTREACHED */ 124 } 125 if ((error = VFS_ROOT(synth_mp, &synth_vp))) { 126 panic("synth: vfs_root failed with %d", error); 127 /* NOTREACHED */ 128 } 129 cache_allocroot(&synth_mp->mnt_ncmountpt, synth_mp, synth_vp); 130 cache_unlock(&synth_mp->mnt_ncmountpt); /* leave ref intact */ 131 vput(synth_vp); 132 133 synth_inited = 1; 134 } 135 136 SYSINIT(synthinit, SI_SUB_VFS, SI_ORDER_ANY, synthinit, NULL); 137